Marduk is the brainchild of Morgan Steinmeyer Håkansson. The Swedish guitarist convened the band in 1990 with the intention of forming the "most brutal and blasphemous metal act ever". The jury is still out on whether or not Marduk has actually achieved that title, but I will admit that they are among the most intense Black Metal acts in existence. Their style has inspired scores of imitators, almost none of whom have been able to break the Norsecore mold.
Not coincidental to their influence, Marduk is also one of the most popular (and commercially successful) bands in Black Metal. They have toured Europe and South America extensively (as often seems to be the case with Scandinavian Metal bands, however, they have had trouble getting into the United States).